Question

My installation

• Ubuntu 10.10
• Rails 3
• gem = sqlite3 and sqlite3-ruby
• gem = mysql2

Now I created a application called mytestapp, using

rails new mytestapp

As usual with rails 3 it defaults to using sqlite3 database. Now I wanted to change the database for mytestapp so that it uses MySql database.

I made changes here

• database.yml
• gemfile – I added gem ‘mysql2’ and removed gem ‘sqlite3’

My new database.yml looked something like this

development:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  database: mytestapp_development
  pool: 5
  username: mytestapp
  password: hacked
  socket: /var/run/mysqld/mysqld.sock

Now I goto localhost:3000 and click on the about application’s development environment
I get the following error

ActiveRecord::ConnectionNotEstablished

MySql user mytestapp has proper permissions for the database.

Infact when I create a new rails app using the following

rails new anotherapp -d mysql

It works great. What can be missing here.

Answer 1

Have you ran bundle install after editing your Gemfile?

If you did, then try to run the following command to see what’s the difference between your hand-edited application and the new you created with -d mysql:

diff /path/to/hand-edited-app /path/to/rails-created-mysql-app